Surfcraft fin assembly

ABSTRACT

A surfcraft fin assembly includes a generally rectangular open mounting box recessed into the underside of surfcraft and having lugs projecting internally at the front and rear of its open edge to retain a notch in the leading edge of the base of the fin and a flexible hook in the rear edge of the base of the fin which flexes allowing insertion into and removal from the mounting box.

FIELD OF THE INVENTION

This invention relates to surfcraft fins and in particular to assemblies for fixing of fins to surfcraft such as surfboards, standup paddle boards and surf skis.

BACKGROUND OF THE INVENTION

It should be noted that reference to the prior art herein is not to be taken as an acknowledgement that such prior art constitutes common general knowledge in the art.

The earliest surfboard fins were made as an integral part of the board. This meant that if a fin became damaged or needed to be changed for a different sized/shaped fin, the job of replacing it involved major reworking. Accordingly various methods of attaching fins to boards were devised to facilitate replacement of the fin.

U.S. Pat. No. 3,516,099 teaches an early example of a removable surfboard fin in which the board has a channeled mounting box recessed into its rear underside. The sidewalls of the box are tapered to receive the complementary base of the fin which is secured in the box by screws at the front and rear of the base. As the screws are tightened the fin is wedged tightly into the box to prevent movement between the fin and the board.

A more recent example is disclosed in US 2010/0173546 wherein a receptacle mounting base receives a connecting section of the fin. The body section of the fin protrudes outside the under surface of the surf board and has front and rear ends inclined outwardly. Two mating blocks which fit over the front and rear protruding sections of the fin are screwed onto the mounting base to secure the fin to the board.

Although the above fins allow replacement of a fin without major reworking of the board, it still takes time to release them from the board and attach a replacement fin.

Clearly it would be advantageous of the present invention to provide a contrivance which ameliorates the disadvantages set forth above or at least provides an alternative to the prior art.

STATEMENT OF THE INVENTION

According to the present invention a surfcraft fin assembly comprises a generally rectangular open mounting box and a fin with a base, the base having a notch in one end and a flexible portion at the other end, the mounting box being adapted to be recessed into the underside of a surfcraft and having two long side edges and short front and rear edges, said front and rear edge having lugs projecting internally to retain the fin in the box by engaging the notch in the base and the flexible portion of the base which flexes to allow insertion into and removal from the mounting box.

Preferably, the flexible portion is biased away from the fin such that during insertion it flexes towards the fin to allow insertion and once pressed past the lug springs away from the fin and under the lug to retain the fin in the mounting box. In one embodiment, the surfcraft fin assembly further includes a lever which can be used to prise the flexible portion of the fin base away from the lug to remove the fin from the mounting box.

In one embodiment, the fin base has a leading edge with a notch and a rear edge with a flexible portion. In an alternative embodiment the fin base has a leading edge with a flexible portion and a rear edge with a notch.

Preferably, the flexible portion is a flexible hook.

Preferably, the lugs are integrally formed with the box. Alternatively, the lugs are removably fastened to the box and are designed to snap off when the fin encounters an obstacle thus releasing the fin. In another embodiment the lugs are screwed into the box and are designed to snap off when the fin encounters an obstacle thus releasing the fin.

In yet another embodiment, the flexible portion of the fin base is adapted to snap off when the fin encounters an obstacle thus releasing the fin.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is now described by way of example only with reference to the accompanying drawings in which:

FIG. 1 is a plan view of a fin sectioned along EE of FIG. 2 and mounted in a mounting box;

FIG. 2 is an elevation corresponding to FIG. 1 sectioned along DD;

FIG. 3 is a plan view of an alternative assembly with a fin sectioned along BB of FIG. 4;

FIG. 4 is an elevation corresponding to FIG. 3 sectioned along AA;

FIG. 5 is an end elevation of a three fin board sectioned along CC of FIG. 4;

FIG. 6 is a plan view of another alternative assembly with a fin sectioned along GG of FIG. 7; and

FIG. 7 is an elevation corresponding to FIG. 6 sectioned along FF.

DETAILED DESCRIPTION OF THE INVENTION

The surfcraft fin assembly shown in FIGS. 1 and 2 comprises mounting box 1 and fin 3. Mounting box 1 is adapted to be recessed into the underside of a surfcraft as shown in FIG. 5 and in particular at the rear of the surfcraft. Box 1 is rectangular and elongated with two long side edges and short front and rear edges. Lugs 2 project internally, into box 1, from the front and rear edge of box 1. Specifically, lugs 2 project from the external surface of the front and rear edge of box 1 such that lugs 2 sit flush with the surface of the board into which box 1 is recessed. Lip 20 projects outwardly, away from box 1, around the side, front and rear edges of box 1. Lip 20 also projects from the external surface of box 1 such that lip 20 sits flush with the surface of the board as shown in FIG. 5.

Fin 3, shown in FIG. 2, is generally planar, has long base 4 and tapers to a point. Fin 3 is adapted to be used with a leading edge that is generally convex in shape, to cut through the water, and a rear edge which is generally concave in shape. Base 4 which fits snugly in box 1 has notch 5 in one end and flexible portion 6 at the other end which flexes to allow insertion into and removal from the mounting box. Notch 5 is ideally in the leading edge of base 4 while flexible portion 6 is in rear edge of base 4 as shown in FIGS. 1 and 2. It would be obvious to a person skilled in the art that a fin of any suitable shape could be also used.

Front lug 2 can engage notch 5 in base 4 and rear lug 2 can engage flexible portion 6 to retain fin 3 in box 1. Notch 5 ensures that base 4 fits tightly under lug 2. Flexible portion 6 is normally biased away from fin 3 such that during insertion into box 1 it flexes towards fin 3 and once pressed past lug 2 it springs away from fin 3 and under lug 2 to retain fin 3 in mounting box 1 as shown in FIG. 2. Flexible portion 6 is formed as a hook which locks under lug 2 thus holding fin 3 securely in place. To remove fin 3 from box 1, a lever (not shown) can be used to prise flexible hook 6 clear from under lug 2 allowing fin 3 to be rotated so that notch 5 clears engagement with front lug 2.

FIGS. 3 and 4 show an alternative fin 11 in which notch 12 is in the rear edge of base 4 and flexible hook 13 is formed in the leading edge. Accordingly notch 12 is first inserted below rear lug 2 and hook 13 flexes to allow engagement with front lug 2.

Box 1 is ideally constructed of a hard plastic but may also be constructed from other suitable hardwearing material. Lugs 2, as shown in FIGS. 1 through 5 are formed as part of box 1. However, FIGS. 6 and 7 show a further alternative in which lugs 15 are removably attached to box 1 and are designed to snap off if fin 16 encounters an obstacle thus releasing fin 16 without major damage and without causing damage to the surfcraft. Specifically, lugs 15 are screwed onto box 1 and snap off if fin 16 encounters an obstacle. New lugs 15 can then be screwed onto box 1 and fin 16 reinserted. Alternatively, flexible hook 13 may be constructed so as to snap off in the event that fin 11 encounters an obstacle, thereby releasing fin 11 from box 1 without damaging box 1, lugs 2 or the surfcraft. New fin 11 can then simply be inserted into box 1 without the need for repairs or adjustments.

A surfcraft may employ only a single fin assembly, for example a surf ski, or may employ a number of assemblies, such as a three finned surfboard 14 as shown in FIG. 5.

It will be obvious that notches 5 and 12 together with flexible portions 6 and 13 allow rapid insertion and removal of fins to and from a surfcraft while maintaining secure engagement with mounting box 1 while the craft is in use. In the case of surfboard 14 with three fins as shown in FIG. 5 the convenience of removal also facilitates transport and storage. Furthermore, the snap off lugs or snap off hook features of the invention are particularly useful in that if the surfcraft encounters an obstacles such as a rock, reef, debris in the water or the like, the fin is released from engagement with box 1 thus preventing damage to the surfcraft or the fin assembly and allowing easy replacement of the fin.

It will be realized that the foregoing has been given by way of illustrative example only and that all other modifications and variations as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth. For example, it would be obvious that alternative methods of engaging the lugs may be used such as flexible protrusions on the base which provide an interference fit with the inside of box 1 or any other suitable arrangement. Alternative methods of joining the lugs to the mounting box may also be used such as clip in lugs or other suitable methods.

Throughout the description and claims of this specification the words “comprise” and variations of that word such as “comprises” and “comprising” are not intended to exclude other additives components integers or steps.

The drawings herein do not display definitive specifications as they are for explanatory and demonstration purposes only. The dimensions, appearance or materials used in this accessory may be varied to suit different surfcraft or fin shapes and sizes. 

1. A surfcraft fin assembly comprising a generally rectangular open mounting box and a fin with a base; the base having a notch in one end and a flexible portion at the other end, the mounting box being adapted to be recessed into the underside of a surfcraft and having two long side edges and short front and rear edges, said front and rear edge having lugs projecting internally to retain the fin in the box by engaging the notch in the base and the flexible portion of the base which flexes to allow insertion into and removal from the mounting box.
 2. The surfcraft fin assembly of claim 1 wherein the flexible portion is biased away from the fin such that during insertion it flexes towards the fin to allow insertion and once pressed past the lug springs away from the fin and under the lug to retain the fin in the mounting box.
 3. The surfcraft fin assembly of claim 1 further comprising a lever which can be used to prise the flexible portion of the fin base away from the lug to remove the fin from the mounting box.
 4. The surfcraft fin assembly of claim 1 wherein the fin base has a leading edge with a notch and a rear edge with a flexible portion.
 5. The surfcraft fin assembly of claim 1 wherein the fin base has a leading edge with a flexible portion and a rear edge with a notch.
 6. The surfcraft fin assembly of claim 1 wherein the flexible portion is a flexible hook.
 7. The surfcraft fin assembly of claim 1 wherein the lugs are integrally formed with the box.
 8. The surfcraft fin assembly of claim 1 in which the lugs are removably fastened to the box and are designed to snap off when the fin encounters an obstacle thus releasing the fin.
 9. The surfcraft fin assembly of claim 1 in which the lugs are screwed into the box and are designed to snap off when the fin encounters an obstacle thus releasing the fin.
 10. The surfcraft fin assembly of claim 1 wherein the flexible portion of the fin base is adapted to snap off when the fin encounters an obstacle thus releasing the fin. 